From the field · Lawn Care & Landscaping
The Mulch Volcano: The Most Common Way Homeowners Kill Their Own Trees.
Drive any street in Huntington in May and you'll see them: neat cones of fresh mulch piled a foot high against tree trunks, little volcanoes with a trunk for a chimney. They photograph as "finished." They read as care. And they're one of the most common ways homeowners lose good trees: slowly, invisibly, five years at a time.
Why a volcano kills
Bark is built to stay dry. It's the tree's raincoat, not its roots. Bury the base of a trunk in mulch and the bark underneath stays damp around the clock, so it softens, then it rots, and the fungi and borers that never trouble a healthy tree now have an open door at ground level.
The second problem is sneakier. Roots grow wherever conditions suit them, and a warm, moist mulch pile suits them fine. So the tree sends roots up into the volcano, and as those roots thicken over the years, they wrap around the trunk that grew them. Arborists call them girdling roots; in plain terms, the tree slowly strangles itself with its own plumbing. A surprising share of our "my tree just looks tired" calls trace back to exactly this, planted years earlier by a spring mulch job.
The ten-second check
Stand at any tree on your property and look at the bottom of the trunk. You should see the root flare: the place where the trunk widens and spreads into the ground, like the base of a wine bottle. If instead the trunk drops into the mulch straight as a telephone pole, the flare is buried, and the countdown has already started.
The fix costs almost nothing
Pull the mulch back until the root flare is visible and the bark is dry. What's left should be a flat donut, not a volcano: two to three inches deep, starting a few inches away from the bark, running out toward the drip line if you like. That's it. Used this way, mulch is genuinely good for a tree: it holds moisture over the roots, where it belongs, buffers soil temperature, and keeps the mower and the string trimmer away from the trunk.
Why crews keep building volcanoes
Because it's fast, it uses up the yards of mulch on the truck, and it looks tidy from the curb on the day the invoice goes out. Nobody is standing there five years later when the canopy thins. If a crew mulches your beds, the instruction to give them is simple and worth saying by name: root flare visible, donut not volcano, nothing touching bark. A crew that pushes back on that is telling you something.
And if you've just checked your own trees and found flares that have been buried for years, don't panic, but don't wait either. Excavating a buried flare and cutting a young girdling root is routine work. We're happy to look; the look is free.